/*!
 *  howler.js v2.0.14
 *  howlerjs.com
 *
 *  (c) 2013-2018, James Simpson of GoldFire Studios
 *  goldfirestudios.com
 *
 *  MIT License
 */

(function() {

    'use strict';

    /** Global Methods **/
    /***************************************************************************/

    /**
     * Create the global controller. All contained methods and properties apply
     * to all sounds that are currently playing or will be in the future.
     */
    var HowlerGlobal = function() {
        this.init();
    };
    HowlerGlobal.prototype = {
        /**
         * Initialize the global Howler object.
         * @return {Howler}
         */
        init: function() {
            var self = this || Howler;

            // Create a global ID counter.
            self._counter = 1000;

            // Internal properties.
            self._codecs = {};
            self._howls = [];
            self._muted = false;
            self._volume = 1;
            self._canPlayEvent = 'canplaythrough';
            self._navigator = (typeof window !== 'undefined' && window.navigator) ? window.navigator : null;

            // Public properties.
            self.masterGain = null;
            self.noAudio = false;
            self.usingWebAudio = true;
            self.autoSuspend = true;
            self.ctx = null;

            // Set to false to disable the auto iOS enabler.
            self.mobileAutoEnable = true;

            // Setup the various state values for global tracking.
            self._setup();

            return self;
        },

        /**
         * Get/set the global volume for all sounds.
         * @param  {Float} vol Volume from 0.0 to 1.0.
         * @return {Howler/Float}     Returns self or current volume.
         */
        volume: function(vol) {
            var self = this || Howler;
            vol = parseFloat(vol);

            // If we don't have an AudioContext created yet, run the setup.
            if (!self.ctx) {
                setupAudioContext();
            }

            if (typeof vol !== 'undefined' && vol >= 0 && vol <= 1) {
                self._volume = vol;

                // Don't update any of the nodes if we are muted.
                if (self._muted) {
                    return self;
                }

                // When using Web Audio, we just need to adjust the master gain.
                if (self.usingWebAudio) {
                    self.masterGain.gain.setValueAtTime(vol, Howler.ctx.currentTime);
                }

                // Loop through and change volume for all HTML5 audio nodes.
                for (var i=0; i<self._howls.length; i++) {
                    if (!self._howls[i]._webAudio) {
                        // Get all of the sounds in this Howl group.
                        var ids = self._howls[i]._getSoundIds();

                        // Loop through all sounds and change the volumes.
                        for (var j=0; j<ids.length; j++) {
                            var sound = self._howls[i]._soundById(ids[j]);

                            if (sound && sound._node) {
                                sound._node.volume = sound._volume * vol;
                            }
                        }
                    }
                }

                return self;
            }

            return self._volume;
        },

        /**
         * Handle muting and unmuting globally.
         * @param  {Boolean} muted Is muted or not.
         */
        mute: function(muted) {
            var self = this || Howler;

            // If we don't have an AudioContext created yet, run the setup.
            if (!self.ctx) {
                setupAudioContext();
            }

            self._muted = muted;

            // With Web Audio, we just need to mute the master gain.
            if (self.usingWebAudio) {
                self.masterGain.gain.setValueAtTime(muted ? 0 : self._volume, Howler.ctx.currentTime);
            }

            // Loop through and mute all HTML5 Audio nodes.
            for (var i=0; i<self._howls.length; i++) {
                if (!self._howls[i]._webAudio) {
                    // Get all of the sounds in this Howl group.
                    var ids = self._howls[i]._getSoundIds();

                    // Loop through all sounds and mark the audio node as muted.
                    for (var j=0; j<ids.length; j++) {
                        var sound = self._howls[i]._soundById(ids[j]);

                        if (sound && sound._node) {
                            sound._node.muted = (muted) ? true : sound._muted;
                        }
                    }
                }
            }

            return self;
        },

        /**
         * Unload and destroy all currently loaded Howl objects.
         * @return {Howler}
         */
        unload: function() {
            var self = this || Howler;

            for (var i=self._howls.length-1; i>=0; i--) {
                self._howls[i].unload();
            }

            // Create a new AudioContext to make sure it is fully reset.
            if (self.usingWebAudio && self.ctx && typeof self.ctx.close !== 'undefined') {
                self.ctx.close();
                self.ctx = null;
                setupAudioContext();
            }

            return self;
        },

        /**
         * Check for codec support of specific extension.
         * @param  {String} ext Audio file extention.
         * @return {Boolean}
         */
        codecs: function(ext) {
            return (this || Howler)._codecs[ext.replace(/^x-/, '')];
        },

        /**
         * Setup various state values for global tracking.
         * @return {Howler}
         */
        _setup: function() {
            var self = this || Howler;

            // Keeps track of the suspend/resume state of the AudioContext.
            self.state = self.ctx ? self.ctx.state || 'running' : 'running';

            // Automatically begin the 30-second suspend process
            self._autoSuspend();

            // Check if audio is available.
            if (!self.usingWebAudio) {
                // No audio is available on this system if noAudio is set to true.
                if (typeof Audio !== 'undefined') {
                    try {
                        var test = new Audio();

                        // Check if the canplaythrough event is available.
                        if (typeof test.oncanplaythrough === 'undefined') {
                            self._canPlayEvent = 'canplay';
                        }
                    } catch(e) {
                        self.noAudio = true;
                    }
                } else {
                    self.noAudio = true;
                }
            }

            // Test to make sure audio isn't disabled in Internet Explorer.
            try {
                var test = new Audio();
                if (test.muted) {
                    self.noAudio = true;
                }
            } catch (e) {}

            // Check for supported codecs.
            if (!self.noAudio) {
                self._setupCodecs();
            }

            return self;
        },

        /**
         * Check for browser support for various codecs and cache the results.
         * @return {Howler}
         */
        _setupCodecs: function() {
            var self = this || Howler;
            var audioTest = null;

            // Must wrap in a try/catch because IE11 in server mode throws an error.
            try {
                audioTest = (typeof Audio !== 'undefined') ? new Audio() : null;
            } catch (err) {
                return self;
            }

            if (!audioTest || typeof audioTest.canPlayType !== 'function') {
                return self;
            }

            var mpegTest = audioTest.canPlayType('audio/mpeg;').replace(/^no$/, '');

            // Opera version <33 has mixed MP3 support, so we need to check for and block it.
            var checkOpera = self._navigator && self._navigator.userAgent.match(/OPR\/([0-6].)/g);
            var isOldOpera = (checkOpera && parseInt(checkOpera[0].split('/')[1], 10) < 33);

            self._codecs = {
                mp3: !!(!isOldOpera && (mpegTest || audioTest.canPlayType('audio/mp3;').replace(/^no$/, ''))),
                mpeg: !!mpegTest,
                opus: !!audioTest.canPlayType('audio/ogg; codecs="opus"').replace(/^no$/, ''),
                ogg: !!audioTest.canPlayType('audio/ogg; codecs="vorbis"').replace(/^no$/, ''),
                oga: !!audioTest.canPlayType('audio/ogg; codecs="vorbis"').replace(/^no$/, ''),
                wav: !!audioTest.canPlayType('audio/wav; codecs="1"').replace(/^no$/, ''),
                aac: !!audioTest.canPlayType('audio/aac;').replace(/^no$/, ''),
                caf: !!audioTest.canPlayType('audio/x-caf;').replace(/^no$/, ''),
                m4a: !!(audioTest.canPlayType('audio/x-m4a;') || audioTest.canPlayType('audio/m4a;') || audioTest.canPlayType('audio/aac;')).replace(/^no$/, ''),
                mp4: !!(audioTest.canPlayType('audio/x-mp4;') || audioTest.canPlayType('audio/mp4;') || audioTest.canPlayType('audio/aac;')).replace(/^no$/, ''),
                weba: !!audioTest.canPlayType('audio/webm; codecs="vorbis"').replace(/^no$/, ''),
                webm: !!audioTest.canPlayType('audio/webm; codecs="vorbis"').replace(/^no$/, ''),
                dolby: !!audioTest.canPlayType('audio/mp4; codecs="ec-3"').replace(/^no$/, ''),
                flac: !!(audioTest.canPlayType('audio/x-flac;') || audioTest.canPlayType('audio/flac;')).replace(/^no$/, '')
            };

            return self;
        },

        /**
         * Mobile browsers will only allow audio to be played after a user interaction.
         * Attempt to automatically unlock audio on the first user interaction.
         * Concept from: http://paulbakaus.com/tutorials/html5/web-audio-on-ios/
         * @return {Howler}
         */
        _enableMobileAudio: function() {
            var self = this || Howler;

            // Only run this on mobile devices if audio isn't already eanbled.
            var isMobile = /iPhone|iPad|iPod|Android|BlackBerry|BB10|Silk|Mobi|Chrome/i.test(self._navigator && self._navigator.userAgent);
            if (self._mobileEnabled || !self.ctx || !isMobile) {
                return;
            }

            self._mobileEnabled = false;
            self.mobileAutoEnable = false;

            // Some mobile devices/platforms have distortion issues when opening/closing tabs and/or web views.
            // Bugs in the browser (especially Mobile Safari) can cause the sampleRate to change from 44100 to 48000.
            // By calling Howler.unload(), we create a new AudioContext with the correct sampleRate.
            if (!self._mobileUnloaded && self.ctx.sampleRate !== 44100) {
                self._mobileUnloaded = true;
                self.unload();
            }

            // Scratch buffer for enabling iOS to dispose of web audio buffers correctly, as per:
            // http://stackoverflow.com/questions/24119684
            self._scratchBuffer = self.ctx.createBuffer(1, 1, 22050);

            // Call this method on touch start to create and play a buffer,
            // then check if the audio actually played to determine if
            // audio has now been unlocked on iOS, Android, etc.
            var unlock = function(e) {
                e.preventDefault();

                // Fix Android can not play in suspend state.
                Howler._autoResume();

                // Create an empty buffer.
                var source = self.ctx.createBufferSource();
                source.buffer = self._scratchBuffer;
                source.connect(self.ctx.destination);

                // Play the empty buffer.
                if (typeof source.start === 'undefined') {
                    source.noteOn(0);
                } else {
                    source.start(0);
                }

                // Calling resume() on a stack initiated by user gesture is what actually unlocks the audio on Android Chrome >= 55.
                if (typeof self.ctx.resume === 'function') {
                    self.ctx.resume();
                }

                // Setup a timeout to check that we are unlocked on the next event loop.
                source.onended = function() {
                    source.disconnect(0);

                    // Update the unlocked state and prevent this check from happening again.
                    self._mobileEnabled = true;

                    // Remove the touch start listener.
                    document.removeEventListener('touchstart', unlock, true);
                    document.removeEventListener('touchend', unlock, true);
                    document.removeEventListener('click', unlock, true);

                    // Let all sounds know that audio has been unlocked.
                    for (var i=0; i<self._howls.length; i++) {
                        self._howls[i]._emit('unlock');
                    }
                };
            };

            // Setup a touch start listener to attempt an unlock in.
            document.addEventListener('touchstart', unlock, true);
            document.addEventListener('touchend', unlock, true);
            document.addEventListener('click', unlock, true);

            return self;
        },

        /**
         * Automatically suspend the Web Audio AudioContext after no sound has played for 30 seconds.
         * This saves processing/energy and fixes various browser-specific bugs with audio getting stuck.
         * @return {Howler}
         */
        _autoSuspend: function() {
            var self = this;

            if (!self.autoSuspend || !self.ctx || typeof self.ctx.suspend === 'undefined' || !Howler.usingWebAudio) {
                return;
            }

            // Check if any sounds are playing.
            for (var i=0; i<self._howls.length; i++) {
                if (self._howls[i]._webAudio) {
                    for (var j=0; j<self._howls[i]._sounds.length; j++) {
                        if (!self._howls[i]._sounds[j]._paused) {
                            return self;
                        }
                    }
                }
            }

            if (self._suspendTimer) {
                clearTimeout(self._suspendTimer);
            }

            // If no sound has played after 30 seconds, suspend the context.
            self._suspendTimer = setTimeout(function() {
                if (!self.autoSuspend) {
                    return;
                }

                self._suspendTimer = null;
                self.state = 'suspending';
                self.ctx.suspend().then(function() {
                    self.state = 'suspended';

                    if (self._resumeAfterSuspend) {
                        delete self._resumeAfterSuspend;
                        self._autoResume();
                    }
                });
            }, 30000);

            return self;
        },

        /**
         * Automatically resume the Web Audio AudioContext when a new sound is played.
         * @return {Howler}
         */
        _autoResume: function() {
            var self = this;

            if (!self.ctx || typeof self.ctx.resume === 'undefined' || !Howler.usingWebAudio) {
                return;
            }

            if (self.state === 'running' && self._suspendTimer) {
                clearTimeout(self._suspendTimer);
                self._suspendTimer = null;
            } else if (self.state === 'suspended') {
                self.ctx.resume().then(function() {
                    self.state = 'running';

                    // Emit to all Howls that the audio has resumed.
                    for (var i=0; i<self._howls.length; i++) {
                        self._howls[i]._emit('resume');
                    }
                });

                if (self._suspendTimer) {
                    clearTimeout(self._suspendTimer);
                    self._suspendTimer = null;
                }
            } else if (self.state === 'suspending') {
                self._resumeAfterSuspend = true;
            }

            return self;
        }
    };

    // Setup the global audio controller.
    var Howler = new HowlerGlobal();

    /** Group Methods **/
    /***************************************************************************/

    /**
     * Create an audio group controller.
     * @param {Object} o Passed in properties for this group.
     */
    var Howl = function(o) {
        var self = this;

        // Throw an error if no source is provided.
        if (!o.src || o.src.length === 0) {
            console.error('An array of source files must be passed with any new Howl.');
            return;
        }

        self.init(o);
    };
    Howl.prototype = {
        /**
         * Initialize a new Howl group object.
         * @param  {Object} o Passed in properties for this group.
         * @return {Howl}
         */
        init: function(o) {
            var self = this;

            // If we don't have an AudioContext created yet, run the setup.
            if (!Howler.ctx) {
                setupAudioContext();
            }

            // Setup user-defined default properties.
            self._autoplay = o.autoplay || false;
            self._format = (typeof o.format !== 'string') ? o.format : [o.format];
            self._html5 = o.html5 || false;
            self._muted = o.mute || false;
            self._loop = o.loop || false;
            self._pool = o.pool || 5;
            self._preload = (typeof o.preload === 'boolean') ? o.preload : true;
            self._rate = o.rate || 1;
            self._sprite = o.sprite || {};
            self._src = (typeof o.src !== 'string') ? o.src : [o.src];
            self._volume = o.volume !== undefined ? o.volume : 1;
            self._xhrWithCredentials = o.xhrWithCredentials || false;

            // Setup all other default properties.
            self._duration = 0;
            self._state = 'unloaded';
            self._sounds = [];
            self._endTimers = {};
            self._queue = [];
            self._playLock = false;

            // Setup event listeners.
            self._onend = o.onend ? [{fn: o.onend}] : [];
            self._onfade = o.onfade ? [{fn: o.onfade}] : [];
            self._onload = o.onload ? [{fn: o.onload}] : [];
            self._onloaderror = o.onloaderror ? [{fn: o.onloaderror}] : [];
            self._onplayerror = o.onplayerror ? [{fn: o.onplayerror}] : [];
            self._onpause = o.onpause ? [{fn: o.onpause}] : [];
            self._onplay = o.onplay ? [{fn: o.onplay}] : [];
            self._onstop = o.onstop ? [{fn: o.onstop}] : [];
            self._onmute = o.onmute ? [{fn: o.onmute}] : [];
            self._onvolume = o.onvolume ? [{fn: o.onvolume}] : [];
            self._onrate = o.onrate ? [{fn: o.onrate}] : [];
            self._onseek = o.onseek ? [{fn: o.onseek}] : [];
            self._onunlock = o.onunlock ? [{fn: o.onunlock}] : [];
            self._onresume = [];

            // Web Audio or HTML5 Audio?
            self._webAudio = Howler.usingWebAudio && !self._html5;

            // Automatically try to enable audio on iOS.
            if (typeof Howler.ctx !== 'undefined' && Howler.ctx && Howler.mobileAutoEnable) {
                Howler._enableMobileAudio();
            }

            // Keep track of this Howl group in the global controller.
            Howler._howls.push(self);

            // If they selected autoplay, add a play event to the load queue.
            if (self._autoplay) {
                self._queue.push({
                    event: 'play',
                    action: function() {
                        self.play();
                    }
                });
            }

            // Load the source file unless otherwise specified.
            if (self._preload) {
                self.load();
            }

            return self;
        },

        /**
         * Load the audio file.
         * @return {Howler}
         */
        load: function() {
            var self = this;
            var url = null;

            // If no audio is available, quit immediately.
            if (Howler.noAudio) {
                self._emit('loaderror', null, 'No audio support.');
                return;
            }

            // Make sure our source is in an array.
            if (typeof self._src === 'string') {
                self._src = [self._src];
            }

            // Loop through the sources and pick the first one that is compatible.
            for (var i=0; i<self._src.length; i++) {
                var ext, str;

                if (self._format && self._format[i]) {
                    // If an extension was specified, use that instead.
                    ext = self._format[i];
                } else {
                    // Make sure the source is a string.
                    str = self._src[i];
                    if (typeof str !== 'string') {
                        self._emit('loaderror', null, 'Non-string found in selected audio sources - ignoring.');
                        continue;
                    }

                    // Extract the file extension from the URL or base64 data URI.
                    ext = /^data:audio\/([^;,]+);/i.exec(str);
                    if (!ext) {
                        ext = /\.([^.]+)$/.exec(str.split('?', 1)[0]);
                    }

                    if (ext) {
                        ext = ext[1].toLowerCase();
                    }
                }

                // Log a warning if no extension was found.
                if (!ext) {
                    console.warn('No file extension was found. Consider using the "format" property or specify an extension.');
                }

                // Check if this extension is available.
                if (ext && Howler.codecs(ext)) {
                    url = self._src[i];
                    break;
                }
            }

            if (!url) {
                self._emit('loaderror', null, 'No codec support for selected audio sources.');
                return;
            }

            self._src = url;
            self._state = 'loading';

            // If the hosting page is HTTPS and the source isn't,
            // drop down to HTML5 Audio to avoid Mixed Content errors.
            if (window.location.protocol === 'https:' && url.slice(0, 5) === 'http:') {
                self._html5 = true;
                self._webAudio = false;
            }

            // Create a new sound object and add it to the pool.
            new Sound(self);

            // Load and decode the audio data for playback.
            if (self._webAudio) {
                loadBuffer(self);
            }

            return self;
        },

        /**
         * Play a sound or resume previous playback.
         * @param  {String/Number} sprite   Sprite name for sprite playback or sound id to continue previous.
         * @param  {Boolean} internal Internal Use: true prevents event firing.
         * @return {Number}          Sound ID.
         */
        play: function(sprite, internal) {
            var self = this;
            var id = null;

            // Determine if a sprite, sound id or nothing was passed
            if (typeof sprite === 'number') {
                id = sprite;
                sprite = null;
            } else if (typeof sprite === 'string' && self._state === 'loaded' && !self._sprite[sprite]) {
                // If the passed sprite doesn't exist, do nothing.
                return null;
            } else if (typeof sprite === 'undefined') {
                // Use the default sound sprite (plays the full audio length).
                sprite = '__default';

                // Check if there is a single paused sound that isn't ended.
                // If there is, play that sound. If not, continue as usual.
                var num = 0;
                for (var i=0; i<self._sounds.length; i++) {
                    if (self._sounds[i]._paused && !self._sounds[i]._ended) {
                        num++;
                        id = self._sounds[i]._id;
                    }
                }

                if (num === 1) {
                    sprite = null;
                } else {
                    id = null;
                }
            }

            // Get the selected node, or get one from the pool.
            var sound = id ? self._soundById(id) : self._inactiveSound();

            // If the sound doesn't exist, do nothing.
            if (!sound) {
                return null;
            }

            // Select the sprite definition.
            if (id && !sprite) {
                sprite = sound._sprite || '__default';
            }

            // If the sound hasn't loaded, we must wait to get the audio's duration.
            // We also need to wait to make sure we don't run into race conditions with
            // the order of function calls.
            if (self._state !== 'loaded') {
                // Set the sprite value on this sound.
                sound._sprite = sprite;

                // Makr this sounded as not ended in case another sound is played before this one loads.
                sound._ended = false;

                // Add the sound to the queue to be played on load.
                var soundId = sound._id;
                self._queue.push({
                    event: 'play',
                    action: function() {
                        self.play(soundId);
                    }
                });

                return soundId;
            }

            // Don't play the sound if an id was passed and it is already playing.
            if (id && !sound._paused) {
                // Trigger the play event, in order to keep iterating through queue.
                if (!internal) {
                    self._loadQueue('play');
                }

                return sound._id;
            }

            // Make sure the AudioContext isn't suspended, and resume it if it is.
            if (self._webAudio) {
                Howler._autoResume();
            }

            // Determine how long to play for and where to start playing.
            var seek = Math.max(0, sound._seek > 0 ? sound._seek : self._sprite[sprite][0] / 1000);
            var duration = Math.max(0, ((self._sprite[sprite][0] + self._sprite[sprite][1]) / 1000) - seek);
            var timeout = (duration * 1000) / Math.abs(sound._rate);

            // Update the parameters of the sound
            sound._paused = false;
            sound._ended = false;
            sound._sprite = sprite;
            sound._seek = seek;
            sound._start = self._sprite[sprite][0] / 1000;
            sound._stop = (self._sprite[sprite][0] + self._sprite[sprite][1]) / 1000;
            sound._loop = !!(sound._loop || self._sprite[sprite][2]);

            // End the sound instantly if seek is at the end.
            if (sound._seek >= sound._stop) {
                self._ended(sound);
                return;
            }

            // Begin the actual playback.
            var node = sound._node;
            if (self._webAudio) {
                // Fire this when the sound is ready to play to begin Web Audio playback.
                var playWebAudio = function() {
                    self._refreshBuffer(sound);

                    // Setup the playback params.
                    var vol = (sound._muted || self._muted) ? 0 : sound._volume;
                    node.gain.setValueAtTime(vol, Howler.ctx.currentTime);
                    sound._playStart = Howler.ctx.currentTime;

                    // Play the sound using the supported method.
                    if (typeof node.bufferSource.start === 'undefined') {
                        sound._loop ? node.bufferSource.noteGrainOn(0, seek, 86400) : node.bufferSource.noteGrainOn(0, seek, duration);
                    } else {
                        sound._loop ? node.bufferSource.start(0, seek, 86400) : node.bufferSource.start(0, seek, duration);
                    }

                    // Start a new timer if none is present.
                    if (timeout !== Infinity) {
                        self._endTimers[sound._id] = setTimeout(self._ended.bind(self, sound), timeout);
                    }

                    if (!internal) {
                        setTimeout(function() {
                            self._emit('play', sound._id);
                        }, 0);
                    }
                };

                if (Howler.state === 'running') {
                    playWebAudio();
                } else {
                    self.once('resume', playWebAudio);

                    // Cancel the end timer.
                    self._clearTimer(sound._id);
                }
            } else {
                // Fire this when the sound is ready to play to begin HTML5 Audio playback.
                var playHtml5 = function() {
                    node.currentTime = seek;
                    node.muted = sound._muted || self._muted || Howler._muted || node.muted;
                    node.volume = sound._volume * Howler.volume();
                    node.playbackRate = sound._rate;

                    // Mobile browsers will throw an error if this is called without user interaction.
                    try {
                        var play = node.play();

                        // Support older browsers that don't support promises, and thus don't have this issue.
                        if (typeof Promise !== 'undefined' && (play instanceof Promise || typeof play.then === 'function')) {
                            // Implements a lock to prevent DOMException: The play() request was interrupted by a call to pause().
                            self._playLock = true;

                            // Releases the lock and executes queued actions.
                            play
                                .then(function() {
                                    self._playLock = false;
                                    if (!internal) {
                                        self._emit('play', sound._id);
                                    }
                                })
                                .catch(function() {
                                    self._playLock = false;
                                    self._emit('playerror', sound._id, 'Playback was unable to start. This is most commonly an issue ' +
                                    'on mobile devices and Chrome where playback was not within a user interaction.');
                                });
                        } else if (!internal) {
                            self._emit('play', sound._id);
                        }

                        // Setting rate before playing won't work in IE, so we set it again here.
                        node.playbackRate = sound._rate;

                        // If the node is still paused, then we can assume there was a playback issue.
                        if (node.paused) {
                            self._emit('playerror', sound._id, 'Playback was unable to start. This is most commonly an issue ' +
                            'on mobile devices and Chrome where playback was not within a user interaction.');
                            return;
                        }

                        // Setup the end timer on sprites or listen for the ended event.
                        if (sprite !== '__default' || sound._loop) {
                            self._endTimers[sound._id] = setTimeout(self._ended.bind(self, sound), timeout);
                        } else {
                            self._endTimers[sound._id] = function() {
                                // Fire ended on this audio node.
                                self._ended(sound);

                                // Clear this listener.
                                node.removeEventListener('ended', self._endTimers[sound._id], false);
                            };
                            node.addEventListener('ended', self._endTimers[sound._id], false);
                        }
                    } catch (err) {
                        self._emit('playerror', sound._id, err);
                    }
                };

                // Play immediately if ready, or wait for the 'canplaythrough'e vent.
                var loadedNoReadyState = (window && window.ejecta) || (!node.readyState && Howler._navigator.isCocoonJS);
                if (node.readyState >= 3 || loadedNoReadyState) {
                    playHtml5();
                } else {
                    var listener = function() {
                        // Begin playback.
                        playHtml5();

                        // Clear this listener.
                        node.removeEventListener(Howler._canPlayEvent, listener, false);
                    };
                    node.addEventListener(Howler._canPlayEvent, listener, false);

                    // Cancel the end timer.
                    self._clearTimer(sound._id);
                }
            }

            return sound._id;
        },

        /**
         * Pause playback and save current position.
         * @param  {Number} id The sound ID (empty to pause all in group).
         * @return {Howl}
         */
        pause: function(id) {
            var self = this;

            // If the sound hasn't loaded or a play() promise is pending, add it to the load queue to pause when capable.
            if (self._state !== 'loaded' || self._playLock) {
                self._queue.push({
                    event: 'pause',
                    action: function() {
                        self.pause(id);
                    }
                });

                return self;
            }

            // If no id is passed, get all ID's to be paused.
            var ids = self._getSoundIds(id);

            for (var i=0; i<ids.length; i++) {
                // Clear the end timer.
                self._clearTimer(ids[i]);

                // Get the sound.
                var sound = self._soundById(ids[i]);

                if (sound && !sound._paused) {
                    // Reset the seek position.
                    sound._seek = self.seek(ids[i]);
                    sound._rateSeek = 0;
                    sound._paused = true;

                    // Stop currently running fades.
                    self._stopFade(ids[i]);

                    if (sound._node) {
                        if (self._webAudio) {
                            // Make sure the sound has been created.
                            if (!sound._node.bufferSource) {
                                continue;
                            }

                            if (typeof sound._node.bufferSource.stop === 'undefined') {
                                sound._node.bufferSource.noteOff(0);
                            } else {
                                sound._node.bufferSource.stop(0);
                            }

                            // Clean up the buffer source.
                            self._cleanBuffer(sound._node);
                        } else if (!isNaN(sound._node.duration) || sound._node.duration === Infinity) {
                            sound._node.pause();
                        }
                    }
                }

                // Fire the pause event, unless `true` is passed as the 2nd argument.
                if (!arguments[1]) {
                    self._emit('pause', sound ? sound._id : null);
                }
            }

            return self;
        },

        /**
         * Stop playback and reset to start.
         * @param  {Number} id The sound ID (empty to stop all in group).
         * @param  {Boolean} internal Internal Use: true prevents event firing.
         * @return {Howl}
         */
        stop: function(id, internal) {
            var self = this;

            // If the sound hasn't loaded, add it to the load queue to stop when capable.
            if (self._state !== 'loaded' || self._playLock) {
                self._queue.push({
                    event: 'stop',
                    action: function() {
                        self.stop(id);
                    }
                });

                return self;
            }

            // If no id is passed, get all ID's to be stopped.
            var ids = self._getSoundIds(id);

            for (var i=0; i<ids.length; i++) {
                // Clear the end timer.
                self._clearTimer(ids[i]);

                // Get the sound.
                var sound = self._soundById(ids[i]);

                if (sound) {
                    // Reset the seek position.
                    sound._seek = sound._start || 0;
                    sound._rateSeek = 0;
                    sound._paused = true;
                    sound._ended = true;

                    // Stop currently running fades.
                    self._stopFade(ids[i]);

                    if (sound._node) {
                        if (self._webAudio) {
                            // Make sure the sound's AudioBufferSourceNode has been created.
                            if (sound._node.bufferSource) {
                                if (typeof sound._node.bufferSource.stop === 'undefined') {
                                    sound._node.bufferSource.noteOff(0);
                                } else {
                                    sound._node.bufferSource.stop(0);
                                }

                                // Clean up the buffer source.
                                self._cleanBuffer(sound._node);
                            }
                        } else if (!isNaN(sound._node.duration) || sound._node.duration === Infinity) {
                            sound._node.currentTime = sound._start || 0;
                            sound._node.pause();
                        }
                    }

                    if (!internal) {
                        self._emit('stop', sound._id);
                    }
                }
            }

            return self;
        },

        /**
         * Mute/unmute a single sound or all sounds in this Howl group.
         * @param  {Boolean} muted Set to true to mute and false to unmute.
         * @param  {Number} id    The sound ID to update (omit to mute/unmute all).
         * @return {Howl}
         */
        mute: function(muted, id) {
            var self = this;

            // If the sound hasn't loaded, add it to the load queue to mute when capable.
            if (self._state !== 'loaded'|| self._playLock) {
                self._queue.push({
                    event: 'mute',
                    action: function() {
                        self.mute(muted, id);
                    }
                });

                return self;
            }

            // If applying mute/unmute to all sounds, update the group's value.
            if (typeof id === 'undefined') {
                if (typeof muted === 'boolean') {
                    self._muted = muted;
                } else {
                    return self._muted;
                }
            }

            // If no id is passed, get all ID's to be muted.
            var ids = self._getSoundIds(id);

            for (var i=0; i<ids.length; i++) {
                // Get the sound.
                var sound = self._soundById(ids[i]);

                if (sound) {
                    sound._muted = muted;

                    // Cancel active fade and set the volume to the end value.
                    if (sound._interval) {
                        self._stopFade(sound._id);
                    }

                    if (self._webAudio && sound._node) {
                        sound._node.gain.setValueAtTime(muted ? 0 : sound._volume, Howler.ctx.currentTime);
                    } else if (sound._node) {
                        sound._node.muted = Howler._muted ? true : muted;
                    }

                    self._emit('mute', sound._id);
                }
            }

            return self;
        },

        /**
         * Get/set the volume of this sound or of the Howl group. This method can optionally take 0, 1 or 2 arguments.
         *   volume() -> Returns the group's volume value.
         *   volume(id) -> Returns the sound id's current volume.
         *   volume(vol) -> Sets the volume of all sounds in this Howl group.
         *   volume(vol, id) -> Sets the volume of passed sound id.
         * @return {Howl/Number} Returns self or current volume.
         */
        volume: function() {
            var self = this;
            var args = arguments;
            var vol, id;

            // Determine the values based on arguments.
            if (args.length === 0) {
                // Return the value of the groups' volume.
                return self._volume;
            } else if (args.length === 1 || args.length === 2 && typeof args[1] === 'undefined') {
                // First check if this is an ID, and if not, assume it is a new volume.
                var ids = self._getSoundIds();
                var index = ids.indexOf(args[0]);
                if (index >= 0) {
                    id = parseInt(args[0], 10);
                } else {
                    vol = parseFloat(args[0]);
                }
            } else if (args.length >= 2) {
                vol = parseFloat(args[0]);
                id = parseInt(args[1], 10);
            }

            // Update the volume or return the current volume.
            var sound;
            if (typeof vol !== 'undefined' && vol >= 0 && vol <= 1) {
                // If the sound hasn't loaded, add it to the load queue to change volume when capable.
                if (self._state !== 'loaded'|| self._playLock) {
                    self._queue.push({
                        event: 'volume',
                        action: function() {
                            self.volume.apply(self, args);
                        }
                    });

                    return self;
                }

                // Set the group volume.
                if (typeof id === 'undefined') {
                    self._volume = vol;
                }

                // Update one or all volumes.
                id = self._getSoundIds(id);
                for (var i=0; i<id.length; i++) {
                    // Get the sound.
                    sound = self._soundById(id[i]);

                    if (sound) {
                        sound._volume = vol;

                        // Stop currently running fades.
                        if (!args[2]) {
                            self._stopFade(id[i]);
                        }

                        if (self._webAudio && sound._node && !sound._muted) {
                            sound._node.gain.setValueAtTime(vol, Howler.ctx.currentTime);
                        } else if (sound._node && !sound._muted) {
                            sound._node.volume = vol * Howler.volume();
                        }

                        self._emit('volume', sound._id);
                    }
                }
            } else {
                sound = id ? self._soundById(id) : self._sounds[0];
                return sound ? sound._volume : 0;
            }

            return self;
        },

        /**
         * Fade a currently playing sound between two volumes (if no id is passsed, all sounds will fade).
         * @param  {Number} from The value to fade from (0.0 to 1.0).
         * @param  {Number} to   The volume to fade to (0.0 to 1.0).
         * @param  {Number} len  Time in milliseconds to fade.
         * @param  {Number} id   The sound id (omit to fade all sounds).
         * @return {Howl}
         */
        fade: function(from, to, len, id) {
            var self = this;

            // If the sound hasn't loaded, add it to the load queue to fade when capable.
            if (self._state !== 'loaded' || self._playLock) {
                self._queue.push({
                    event: 'fade',
                    action: function() {
                        self.fade(from, to, len, id);
                    }
                });

                return self;
            }

            // Set the volume to the start position.
            self.volume(from, id);

            // Fade the volume of one or all sounds.
            var ids = self._getSoundIds(id);
            for (var i=0; i<ids.length; i++) {
                // Get the sound.
                var sound = self._soundById(ids[i]);

                // Create a linear fade or fall back to timeouts with HTML5 Audio.
                if (sound) {
                    // Stop the previous fade if no sprite is being used (otherwise, volume handles this).
                    if (!id) {
                        self._stopFade(ids[i]);
                    }

                    // If we are using Web Audio, let the native methods do the actual fade.
                    if (self._webAudio && !sound._muted) {
                        var currentTime = Howler.ctx.currentTime;
                        var end = currentTime + (len / 1000);
                        sound._volume = from;
                        sound._node.gain.setValueAtTime(from, currentTime);
                        sound._node.gain.linearRampToValueAtTime(to, end);
                    }

                    self._startFadeInterval(sound, from, to, len, ids[i], typeof id === 'undefined');
                }
            }

            return self;
        },

        /**
         * Starts the internal interval to fade a sound.
         * @param  {Object} sound Reference to sound to fade.
         * @param  {Number} from The value to fade from (0.0 to 1.0).
         * @param  {Number} to   The volume to fade to (0.0 to 1.0).
         * @param  {Number} len  Time in milliseconds to fade.
         * @param  {Number} id   The sound id to fade.
         * @param  {Boolean} isGroup   If true, set the volume on the group.
         */
        _startFadeInterval: function(sound, from, to, len, id, isGroup) {
            var self = this;
            var vol = from;
            var diff = to - from;
            var steps = Math.abs(diff / 0.01);
            var stepLen = Math.max(4, (steps > 0) ? len / steps : len);
            var lastTick = Date.now();

            // Store the value being faded to.
            sound._fadeTo = to;

            // Update the volume value on each interval tick.
            sound._interval = setInterval(function() {
                // Update the volume based on the time since the last tick.
                var tick = (Date.now() - lastTick) / len;
                lastTick = Date.now();
                vol += diff * tick;

                // Make sure the volume is in the right bounds.
                vol = Math.max(0, vol);
                vol = Math.min(1, vol);

                // Round to within 2 decimal points.
                vol = Math.round(vol * 100) / 100;

                // Change the volume.
                if (self._webAudio) {
                    sound._volume = vol;
                } else {
                    self.volume(vol, sound._id, true);
                }

                // Set the group's volume.
                if (isGroup) {
                    self._volume = vol;
                }

                // When the fade is complete, stop it and fire event.
                if ((to < from && vol <= to) || (to > from && vol >= to)) {
                    clearInterval(sound._interval);
                    sound._interval = null;
                    sound._fadeTo = null;
                    self.volume(to, sound._id);
                    self._emit('fade', sound._id);
                }
            }, stepLen);
        },

        /**
         * Internal method that stops the currently playing fade when
         * a new fade starts, volume is changed or the sound is stopped.
         * @param  {Number} id The sound id.
         * @return {Howl}
         */
        _stopFade: function(id) {
            var self = this;
            var sound = self._soundById(id);

            if (sound && sound._interval) {
                if (self._webAudio) {
                    sound._node.gain.cancelScheduledValues(Howler.ctx.currentTime);
                }

                clearInterval(sound._interval);
                sound._interval = null;
                self.volume(sound._fadeTo, id);
                sound._fadeTo = null;
                self._emit('fade', id);
            }

            return self;
        },

        /**
         * Get/set the loop parameter on a sound. This method can optionally take 0, 1 or 2 arguments.
         *   loop() -> Returns the group's loop value.
         *   loop(id) -> Returns the sound id's loop value.
         *   loop(loop) -> Sets the loop value for all sounds in this Howl group.
         *   loop(loop, id) -> Sets the loop value of passed sound id.
         * @return {Howl/Boolean} Returns self or current loop value.
         */
        loop: function() {
            var self = this;
            var args = arguments;
            var loop, id, sound;

            // Determine the values for loop and id.
            if (args.length === 0) {
                // Return the grou's loop value.
                return self._loop;
            } else if (args.length === 1) {
                if (typeof args[0] === 'boolean') {
                    loop = args[0];
                    self._loop = loop;
                } else {
                    // Return this sound's loop value.
                    sound = self._soundById(parseInt(args[0], 10));
                    return sound ? sound._loop : false;
                }
            } else if (args.length === 2) {
                loop = args[0];
                id = parseInt(args[1], 10);
            }

            // If no id is passed, get all ID's to be looped.
            var ids = self._getSoundIds(id);
            for (var i=0; i<ids.length; i++) {
                sound = self._soundById(ids[i]);

                if (sound) {
                    sound._loop = loop;
                    if (self._webAudio && sound._node && sound._node.bufferSource) {
                        sound._node.bufferSource.loop = loop;
                        if (loop) {
                            sound._node.bufferSource.loopStart = sound._start || 0;
                            sound._node.bufferSource.loopEnd = sound._stop;
                        }
                    }
                }
            }

            return self;
        },

        /**
         * Get/set the playback rate of a sound. This method can optionally take 0, 1 or 2 arguments.
         *   rate() -> Returns the first sound node's current playback rate.
         *   rate(id) -> Returns the sound id's current playback rate.
         *   rate(rate) -> Sets the playback rate of all sounds in this Howl group.
         *   rate(rate, id) -> Sets the playback rate of passed sound id.
         * @return {Howl/Number} Returns self or the current playback rate.
         */
        rate: function() {
            var self = this;
            var args = arguments;
            var rate, id;

            // Determine the values based on arguments.
            if (args.length === 0) {
                // We will simply return the current rate of the first node.
                id = self._sounds[0]._id;
            } else if (args.length === 1) {
                // First check if this is an ID, and if not, assume it is a new rate value.
                var ids = self._getSoundIds();
                var index = ids.indexOf(args[0]);
                if (index >= 0) {
                    id = parseInt(args[0], 10);
                } else {
                    rate = parseFloat(args[0]);
                }
            } else if (args.length === 2) {
                rate = parseFloat(args[0]);
                id = parseInt(args[1], 10);
            }

            // Update the playback rate or return the current value.
            var sound;
            if (typeof rate === 'number') {
                // If the sound hasn't loaded, add it to the load queue to change playback rate when capable.
                if (self._state !== 'loaded' || self._playLock) {
                    self._queue.push({
                        event: 'rate',
                        action: function() {
                            self.rate.apply(self, args);
                        }
                    });

                    return self;
                }

                // Set the group rate.
                if (typeof id === 'undefined') {
                    self._rate = rate;
                }

                // Update one or all volumes.
                id = self._getSoundIds(id);
                for (var i=0; i<id.length; i++) {
                    // Get the sound.
                    sound = self._soundById(id[i]);

                    if (sound) {
                        // Keep track of our position when the rate changed and update the playback
                        // start position so we can properly adjust the seek position for time elapsed.
                        sound._rateSeek = self.seek(id[i]);
                        sound._playStart = self._webAudio ? Howler.ctx.currentTime : sound._playStart;
                        sound._rate = rate;

                        // Change the playback rate.
                        if (self._webAudio && sound._node && sound._node.bufferSource) {
                            sound._node.bufferSource.playbackRate.setValueAtTime(rate, Howler.ctx.currentTime);
                        } else if (sound._node) {
                            sound._node.playbackRate = rate;
                        }

                        // Reset the timers.
                        var seek = self.seek(id[i]);
                        var duration = ((self._sprite[sound._sprite][0] + self._sprite[sound._sprite][1]) / 1000) - seek;
                        var timeout = (duration * 1000) / Math.abs(sound._rate);

                        // Start a new end timer if sound is already playing.
                        if (self._endTimers[id[i]] || !sound._paused) {
                            self._clearTimer(id[i]);
                            self._endTimers[id[i]] = setTimeout(self._ended.bind(self, sound), timeout);
                        }

                        self._emit('rate', sound._id);
                    }
                }
            } else {
                sound = self._soundById(id);
                return sound ? sound._rate : self._rate;
            }

            return self;
        },

        /**
         * Get/set the seek position of a sound. This method can optionally take 0, 1 or 2 arguments.
         *   seek() -> Returns the first sound node's current seek position.
         *   seek(id) -> Returns the sound id's current seek position.
         *   seek(seek) -> Sets the seek position of the first sound node.
         *   seek(seek, id) -> Sets the seek position of passed sound id.
         * @return {Howl/Number} Returns self or the current seek position.
         */
        seek: function() {
            var self = this;
            var args = arguments;
            var seek, id;

            // Determine the values based on arguments.
            if (args.length === 0) {
                // We will simply return the current position of the first node.
                id = self._sounds[0]._id;
            } else if (args.length === 1) {
                // First check if this is an ID, and if not, assume it is a new seek position.
                var ids = self._getSoundIds();
                var index = ids.indexOf(args[0]);
                if (index >= 0) {
                    id = parseInt(args[0], 10);
                } else if (self._sounds.length) {
                    id = self._sounds[0]._id;
                    seek = parseFloat(args[0]);
                }
            } else if (args.length === 2) {
                seek = parseFloat(args[0]);
                id = parseInt(args[1], 10);
            }

            // If there is no ID, bail out.
            if (typeof id === 'undefined') {
                return self;
            }

            // If the sound hasn't loaded, add it to the load queue to seek when capable.
            if (self._state !== 'loaded' || self._playLock) {
                self._queue.push({
                    event: 'seek',
                    action: function() {
                        self.seek.apply(self, args);
                    }
                });

                return self;
            }

            // Get the sound.
            var sound = self._soundById(id);

            if (sound) {
                if (typeof seek === 'number' && seek >= 0) {
                    // Pause the sound and update position for restarting playback.
                    var playing = self.playing(id);
                    if (playing) {
                        self.pause(id, true);
                    }

                    // Move the position of the track and cancel timer.
                    sound._seek = seek;
                    sound._ended = false;
                    self._clearTimer(id);

                    // Update the seek position for HTML5 Audio.
                    if (!self._webAudio && sound._node) {
                        sound._node.currentTime = seek;
                    }

                    // Seek and emit when ready.
                    var seekAndEmit = function() {
                        self._emit('seek', id);

                        // Restart the playback if the sound was playing.
                        if (playing) {
                            self.play(id, true);
                        }
                    };

                    // Wait for the play lock to be unset before emitting (HTML5 Audio).
                    if (playing && !self._webAudio) {
                        var emitSeek = function() {
                            if (!self._playLock) {
                                seekAndEmit();
                            } else {
                                setTimeout(emitSeek, 0);
                            }
                        };
                        setTimeout(emitSeek, 0);
                    } else {
                        seekAndEmit();
                    }
                } else {
                    if (self._webAudio) {
                        var realTime = self.playing(id) ? Howler.ctx.currentTime - sound._playStart : 0;
                        var rateSeek = sound._rateSeek ? sound._rateSeek - sound._seek : 0;
                        return sound._seek + (rateSeek + realTime * Math.abs(sound._rate));
                    } else {
                        return sound._node.currentTime;
                    }
                }
            }

            return self;
        },

        /**
         * Check if a specific sound is currently playing or not (if id is provided), or check if at least one of the sounds in the group is playing or not.
         * @param  {Number}  id The sound id to check. If none is passed, the whole sound group is checked.
         * @return {Boolean} True if playing and false if not.
         */
        playing: function(id) {
            var self = this;

            // Check the passed sound ID (if any).
            if (typeof id === 'number') {
                var sound = self._soundById(id);
                return sound ? !sound._paused : false;
            }

            // Otherwise, loop through all sounds and check if any are playing.
            for (var i=0; i<self._sounds.length; i++) {
                if (!self._sounds[i]._paused) {
                    return true;
                }
            }

            return false;
        },

        /**
         * Get the duration of this sound. Passing a sound id will return the sprite duration.
         * @param  {Number} id The sound id to check. If none is passed, return full source duration.
         * @return {Number} Audio duration in seconds.
         */
        duration: function(id) {
            var self = this;
            var duration = self._duration;

            // If we pass an ID, get the sound and return the sprite length.
            var sound = self._soundById(id);
            if (sound) {
                duration = self._sprite[sound._sprite][1] / 1000;
            }

            return duration;
        },

        /**
         * Returns the current loaded state of this Howl.
         * @return {String} 'unloaded', 'loading', 'loaded'
         */
        state: function() {
            return this._state;
        },

        /**
         * Unload and destroy the current Howl object.
         * This will immediately stop all sound instances attached to this group.
         */
        unload: function() {
            var self = this;

            // Stop playing any active sounds.
            var sounds = self._sounds;
            for (var i=0; i<sounds.length; i++) {
                // Stop the sound if it is currently playing.
                if (!sounds[i]._paused) {
                    self.stop(sounds[i]._id);
                }

                // Remove the source or disconnect.
                if (!self._webAudio) {
                    // Set the source to 0-second silence to stop any downloading (except in IE).
                    var checkIE = /MSIE |Trident\//.test(Howler._navigator && Howler._navigator.userAgent);
                    if (!checkIE) {
                        sounds[i]._node.src = 'data:audio/wav;base64,UklGRigAAABXQVZFZm10IBIAAAABAAEARKwAAIhYAQACABAAAABkYXRhAgAAAAEA';
                    }

                    // Remove any event listeners.
                    sounds[i]._node.removeEventListener('error', sounds[i]._errorFn, false);
                    sounds[i]._node.removeEventListener(Howler._canPlayEvent, sounds[i]._loadFn, false);
                }

                // Empty out all of the nodes.
                delete sounds[i]._node;

                // Make sure all timers are cleared out.
                self._clearTimer(sounds[i]._id);
            }

            // Remove the references in the global Howler object.
            var index = Howler._howls.indexOf(self);
            if (index >= 0) {
                Howler._howls.splice(index, 1);
            }

            // Delete this sound from the cache (if no other Howl is using it).
            var remCache = true;
            for (i=0; i<Howler._howls.length; i++) {
                if (Howler._howls[i]._src === self._src) {
                    remCache = false;
                    break;
                }
            }

            if (cache && remCache) {
                delete cache[self._src];
            }

            // Clear global errors.
            Howler.noAudio = false;

            // Clear out `self`.
            self._state = 'unloaded';
            self._sounds = [];
            self = null;

            return null;
        },

        /**
         * Listen to a custom event.
         * @param  {String}   event Event name.
         * @param  {Function} fn    Listener to call.
         * @param  {Number}   id    (optional) Only listen to events for this sound.
         * @param  {Number}   once  (INTERNAL) Marks event to fire only once.
         * @return {Howl}
         */
        on: function(event, fn, id, once) {
            var self = this;
            var events = self['_on' + event];

            if (typeof fn === 'function') {
                events.push(once ? {id: id, fn: fn, once: once} : {id: id, fn: fn});
            }

            return self;
        },

        /**
         * Remove a custom event. Call without parameters to remove all events.
         * @param  {String}   event Event name.
         * @param  {Function} fn    Listener to remove. Leave empty to remove all.
         * @param  {Number}   id    (optional) Only remove events for this sound.
         * @return {Howl}
         */
        off: function(event, fn, id) {
            var self = this;
            var events = self['_on' + event];
            var i = 0;

            // Allow passing just an event and ID.
            if (typeof fn === 'number') {
                id = fn;
                fn = null;
            }

            if (fn || id) {
                // Loop through event store and remove the passed function.
                for (i=0; i<events.length; i++) {
                    var isId = (id === events[i].id);
                    if (fn === events[i].fn && isId || !fn && isId) {
                        events.splice(i, 1);
                        break;
                    }
                }
            } else if (event) {
                // Clear out all events of this type.
                self['_on' + event] = [];
            } else {
                // Clear out all events of every type.
                var keys = Object.keys(self);
                for (i=0; i<keys.length; i++) {
                    if ((keys[i].indexOf('_on') === 0) && Array.isArray(self[keys[i]])) {
                        self[keys[i]] = [];
                    }
                }
            }

            return self;
        },

        /**
         * Listen to a custom event and remove it once fired.
         * @param  {String}   event Event name.
         * @param  {Function} fn    Listener to call.
         * @param  {Number}   id    (optional) Only listen to events for this sound.
         * @return {Howl}
         */
        once: function(event, fn, id) {
            var self = this;

            // Setup the event listener.
            self.on(event, fn, id, 1);

            return self;
        },

        /**
         * Emit all events of a specific type and pass the sound id.
         * @param  {String} event Event name.
         * @param  {Number} id    Sound ID.
         * @param  {Number} msg   Message to go with event.
         * @return {Howl}
         */
        _emit: function(event, id, msg) {
            var self = this;
            var events = self['_on' + event];

            // Loop through event store and fire all functions.
            for (var i=events.length-1; i>=0; i--) {
                // Only fire the listener if the correct ID is used.
                if (!events[i].id || events[i].id === id || event === 'load') {
                    setTimeout(function(fn) {
                        fn.call(this, id, msg);
                    }.bind(self, events[i].fn), 0);

                    // If this event was setup with `once`, remove it.
                    if (events[i].once) {
                        self.off(event, events[i].fn, events[i].id);
                    }
                }
            }

            // Pass the event type into load queue so that it can continue stepping.
            self._loadQueue(event);

            return self;
        },

        /**
         * Queue of actions initiated before the sound has loaded.
         * These will be called in sequence, with the next only firing
         * after the previous has finished executing (even if async like play).
         * @return {Howl}
         */
        _loadQueue: function(event) {
            var self = this;

            if (self._queue.length > 0) {
                var task = self._queue[0];

                // Remove this task if a matching event was passed.
                if (task.event === event) {
                    self._queue.shift();
                    self._loadQueue();
                }

                // Run the task if no event type is passed.
                if (!event) {
                    task.action();
                }
            }

            return self;
        },

        /**
         * Fired when playback ends at the end of the duration.
         * @param  {Sound} sound The sound object to work with.
         * @return {Howl}
         */
        _ended: function(sound) {
            var self = this;
            var sprite = sound._sprite;

            // If we are using IE and there was network latency we may be clipping
            // audio before it completes playing. Lets check the node to make sure it
            // believes it has completed, before ending the playback.
            if (!self._webAudio && sound._node && !sound._node.paused && !sound._node.ended && sound._node.currentTime < sound._stop) {
                setTimeout(self._ended.bind(self, sound), 100);
                return self;
            }

            // Should this sound loop?
            var loop = !!(sound._loop || self._sprite[sprite][2]);

            // Fire the ended event.
            self._emit('end', sound._id);

            // Restart the playback for HTML5 Audio loop.
            if (!self._webAudio && loop) {
                self.stop(sound._id, true).play(sound._id);
            }

            // Restart this timer if on a Web Audio loop.
            if (self._webAudio && loop) {
                self._emit('play', sound._id);
                sound._seek = sound._start || 0;
                sound._rateSeek = 0;
                sound._playStart = Howler.ctx.currentTime;

                var timeout = ((sound._stop - sound._start) * 1000) / Math.abs(sound._rate);
                self._endTimers[sound._id] = setTimeout(self._ended.bind(self, sound), timeout);
            }

            // Mark the node as paused.
            if (self._webAudio && !loop) {
                sound._paused = true;
                sound._ended = true;
                sound._seek = sound._start || 0;
                sound._rateSeek = 0;
                self._clearTimer(sound._id);

                // Clean up the buffer source.
                self._cleanBuffer(sound._node);

                // Attempt to auto-suspend AudioContext if no sounds are still playing.
                Howler._autoSuspend();
            }

            // When using a sprite, end the track.
            if (!self._webAudio && !loop) {
                self.stop(sound._id, true);
            }

            return self;
        },

        /**
         * Clear the end timer for a sound playback.
         * @param  {Number} id The sound ID.
         * @return {Howl}
         */
        _clearTimer: function(id) {
            var self = this;

            if (self._endTimers[id]) {
                // Clear the timeout or remove the ended listener.
                if (typeof self._endTimers[id] !== 'function') {
                    clearTimeout(self._endTimers[id]);
                } else {
                    var sound = self._soundById(id);
                    if (sound && sound._node) {
                        sound._node.removeEventListener('ended', self._endTimers[id], false);
                    }
                }

                delete self._endTimers[id];
            }

            return self;
        },

        /**
         * Return the sound identified by this ID, or return null.
         * @param  {Number} id Sound ID
         * @return {Object}    Sound object or null.
         */
        _soundById: function(id) {
            var self = this;

            // Loop through all sounds and find the one with this ID.
            for (var i=0; i<self._sounds.length; i++) {
                if (id === self._sounds[i]._id) {
                    return self._sounds[i];
                }
            }

            return null;
        },

        /**
         * Return an inactive sound from the pool or create a new one.
         * @return {Sound} Sound playback object.
         */
        _inactiveSound: function() {
            var self = this;

            self._drain();

            // Find the first inactive node to recycle.
            for (var i=0; i<self._sounds.length; i++) {
                if (self._sounds[i]._ended) {
                    return self._sounds[i].reset();
                }
            }

            // If no inactive node was found, create a new one.
            return new Sound(self);
        },

        /**
         * Drain excess inactive sounds from the pool.
         */
        _drain: function() {
            var self = this;
            var limit = self._pool;
            var cnt = 0;
            var i = 0;

            // If there are less sounds than the max pool size, we are done.
            if (self._sounds.length < limit) {
                return;
            }

            // Count the number of inactive sounds.
            for (i=0; i<self._sounds.length; i++) {
                if (self._sounds[i]._ended) {
                    cnt++;
                }
            }

            // Remove excess inactive sounds, going in reverse order.
            for (i=self._sounds.length - 1; i>=0; i--) {
                if (cnt <= limit) {
                    return;
                }

                if (self._sounds[i]._ended) {
                    // Disconnect the audio source when using Web Audio.
                    if (self._webAudio && self._sounds[i]._node) {
                        self._sounds[i]._node.disconnect(0);
                    }

                    // Remove sounds until we have the pool size.
                    self._sounds.splice(i, 1);
                    cnt--;
                }
            }
        },

        /**
         * Get all ID's from the sounds pool.
         * @param  {Number} id Only return one ID if one is passed.
         * @return {Array}    Array of IDs.
         */
        _getSoundIds: function(id) {
            var self = this;

            if (typeof id === 'undefined') {
                var ids = [];
                for (var i=0; i<self._sounds.length; i++) {
                    ids.push(self._sounds[i]._id);
                }

                return ids;
            } else {
                return [id];
            }
        },

        /**
         * Load the sound back into the buffer source.
         * @param  {Sound} sound The sound object to work with.
         * @return {Howl}
         */
        _refreshBuffer: function(sound) {
            var self = this;

            // Setup the buffer source for playback.
            sound._node.bufferSource = Howler.ctx.createBufferSource();
            sound._node.bufferSource.buffer = cache[self._src];

            // Connect to the correct node.
            if (sound._panner) {
                sound._node.bufferSource.connect(sound._panner);
            } else {
                sound._node.bufferSource.connect(sound._node);
            }

            // Setup looping and playback rate.
            sound._node.bufferSource.loop = sound._loop;
            if (sound._loop) {
                sound._node.bufferSource.loopStart = sound._start || 0;
                sound._node.bufferSource.loopEnd = sound._stop || 0;
            }
            sound._node.bufferSource.playbackRate.setValueAtTime(sound._rate, Howler.ctx.currentTime);

            return self;
        },

        /**
         * Prevent memory leaks by cleaning up the buffer source after playback.
         * @param  {Object} node Sound's audio node containing the buffer source.
         * @return {Howl}
         */
        _cleanBuffer: function(node) {
            var self = this;

            if (Howler._scratchBuffer && node.bufferSource) {
                node.bufferSource.onended = null;
                node.bufferSource.disconnect(0);
                try { node.bufferSource.buffer = Howler._scratchBuffer; } catch(e) {}
            }
            node.bufferSource = null;

            return self;
        }
    };

    /** Single Sound Methods **/
    /***************************************************************************/

    /**
     * Setup the sound object, which each node attached to a Howl group is contained in.
     * @param {Object} howl The Howl parent group.
     */
    var Sound = function(howl) {
        this._parent = howl;
        this.init();
    };
    Sound.prototype = {
        /**
         * Initialize a new Sound object.
         * @return {Sound}
         */
        init: function() {
            var self = this;
            var parent = self._parent;

            // Setup the default parameters.
            self._muted = parent._muted;
            self._loop = parent._loop;
            self._volume = parent._volume;
            self._rate = parent._rate;
            self._seek = 0;
            self._paused = true;
            self._ended = true;
            self._sprite = '__default';

            // Generate a unique ID for this sound.
            self._id = ++Howler._counter;

            // Add itself to the parent's pool.
            parent._sounds.push(self);

            // Create the new node.
            self.create();

            return self;
        },

        /**
         * Create and setup a new sound object, whether HTML5 Audio or Web Audio.
         * @return {Sound}
         */
        create: function() {
            var self = this;
            var parent = self._parent;
            var volume = (Howler._muted || self._muted || self._parent._muted) ? 0 : self._volume;

            if (parent._webAudio) {
                // Create the gain node for controlling volume (the source will connect to this).
                self._node = (typeof Howler.ctx.createGain === 'undefined') ? Howler.ctx.createGainNode() : Howler.ctx.createGain();
                self._node.gain.setValueAtTime(volume, Howler.ctx.currentTime);
                self._node.paused = true;
                self._node.connect(Howler.masterGain);
            } else {
                self._node = new Audio();

                // Listen for errors (http://dev.w3.org/html5/spec-author-view/spec.html#mediaerror).
                self._errorFn = self._errorListener.bind(self);
                self._node.addEventListener('error', self._errorFn, false);

                // Listen for 'canplaythrough' event to let us know the sound is ready.
                self._loadFn = self._loadListener.bind(self);
                self._node.addEventListener(Howler._canPlayEvent, self._loadFn, false);

                // Setup the new audio node.
                self._node.src = parent._src;
                self._node.preload = 'auto';
                self._node.volume = volume * Howler.volume();

                // Begin loading the source.
                self._node.load();
            }

            return self;
        },

        /**
         * Reset the parameters of this sound to the original state (for recycle).
         * @return {Sound}
         */
        reset: function() {
            var self = this;
            var parent = self._parent;

            // Reset all of the parameters of this sound.
            self._muted = parent._muted;
            self._loop = parent._loop;
            self._volume = parent._volume;
            self._rate = parent._rate;
            self._seek = 0;
            self._rateSeek = 0;
            self._paused = true;
            self._ended = true;
            self._sprite = '__default';

            // Generate a new ID so that it isn't confused with the previous sound.
            self._id = ++Howler._counter;

            return self;
        },

        /**
         * HTML5 Audio error listener callback.
         */
        _errorListener: function() {
            var self = this;

            // Fire an error event and pass back the code.
            self._parent._emit('loaderror', self._id, self._node.error ? self._node.error.code : 0);

            // Clear the event listener.
            self._node.removeEventListener('error', self._errorFn, false);
        },

        /**
         * HTML5 Audio canplaythrough listener callback.
         */
        _loadListener: function() {
            var self = this;
            var parent = self._parent;

            // Round up the duration to account for the lower precision in HTML5 Audio.
            parent._duration = Math.ceil(self._node.duration * 10) / 10;

            // Setup a sprite if none is defined.
            if (Object.keys(parent._sprite).length === 0) {
                parent._sprite = {__default: [0, parent._duration * 1000]};
            }

            if (parent._state !== 'loaded') {
                parent._state = 'loaded';
                parent._emit('load');
                parent._loadQueue();
            }

            // Clear the event listener.
            self._node.removeEventListener(Howler._canPlayEvent, self._loadFn, false);
        }
    };

    /** Helper Methods **/
    /***************************************************************************/

    var cache = {};

    /**
     * Buffer a sound from URL, Data URI or cache and decode to audio source (Web Audio API).
     * @param  {Howl} self
     */
    var loadBuffer = function(self) {
        var url = self._src;

        // Check if the buffer has already been cached and use it instead.
        if (cache[url]) {
            // Set the duration from the cache.
            self._duration = cache[url].duration;

            // Load the sound into this Howl.
            loadSound(self);

            return;
        }

        if (/^data:[^;]+;base64,/.test(url)) {
            // Decode the base64 data URI without XHR, since some browsers don't support it.
            var data = atob(url.split(',')[1]);
            var dataView = new Uint8Array(data.length);
            for (var i=0; i<data.length; ++i) {
                dataView[i] = data.charCodeAt(i);
            }

            decodeAudioData(dataView.buffer, self);
        } else {
            // Load the buffer from the URL.
            var xhr = new XMLHttpRequest();
            xhr.open('GET', url, true);
            xhr.withCredentials = self._xhrWithCredentials;
            xhr.responseType = 'arraybuffer';
            xhr.onload = function() {
                // Make sure we get a successful response back.
                var code = (xhr.status + '')[0];
                if (code !== '0' && code !== '2' && code !== '3') {
                    self._emit('loaderror', null, 'Failed loading audio file with status: ' + xhr.status + '.');
                    return;
                }

                decodeAudioData(xhr.response, self);
            };
            xhr.onerror = function() {
                // If there is an error, switch to HTML5 Audio.
                if (self._webAudio) {
                    self._html5 = true;
                    self._webAudio = false;
                    self._sounds = [];
                    delete cache[url];
                    self.load();
                }
            };
            safeXhrSend(xhr);
        }
    };

    /**
     * Send the XHR request wrapped in a try/catch.
     * @param  {Object} xhr XHR to send.
     */
    var safeXhrSend = function(xhr) {
        try {
            xhr.send();
        } catch (e) {
            xhr.onerror();
        }
    };

    /**
     * Decode audio data from an array buffer.
     * @param  {ArrayBuffer} arraybuffer The audio data.
     * @param  {Howl}        self
     */
    var decodeAudioData = function(arraybuffer, self) {
        // Load the sound on success.
        var success = function(buffer) {
            if (buffer && self._sounds.length > 0) {
                cache[self._src] = buffer;
                loadSound(self, buffer);
            } else {
                onError();
            }
        };

        // Fire a load error if something broke.
        var error = function() {
            self._emit('loaderror', null, 'Decoding audio data failed.');
        };

        // Decode the buffer into an audio source.
        if (typeof Promise !== 'undefined' && Howler.ctx.decodeAudioData.length === 1) {
            Howler.ctx.decodeAudioData(arraybuffer).then(success).catch(error);
        } else {
            Howler.ctx.decodeAudioData(arraybuffer, success, error);
        }
    }

    /**
     * Sound is now loaded, so finish setting everything up and fire the loaded event.
     * @param  {Howl} self
     * @param  {Object} buffer The decoded buffer sound source.
     */
    var loadSound = function(self, buffer) {
        // Set the duration.
        if (buffer && !self._duration) {
            self._duration = buffer.duration;
        }

        // Setup a sprite if none is defined.
        if (Object.keys(self._sprite).length === 0) {
            self._sprite = {__default: [0, self._duration * 1000]};
        }

        // Fire the loaded event.
        if (self._state !== 'loaded') {
            self._state = 'loaded';
            self._emit('load');
            self._loadQueue();
        }
    };

    /**
     * Setup the audio context when available, or switch to HTML5 Audio mode.
     */
    var setupAudioContext = function() {
        // Check if we are using Web Audio and setup the AudioContext if we are.
        try {
            if (typeof AudioContext !== 'undefined') {
                Howler.ctx = new AudioContext();
            } else if (typeof webkitAudioContext !== 'undefined') {
                Howler.ctx = new webkitAudioContext();
            } else {
                Howler.usingWebAudio = false;
            }
        } catch(e) {
            Howler.usingWebAudio = false;
        }

        // Check if a webview is being used on iOS8 or earlier (rather than the browser).
        // If it is, disable Web Audio as it causes crashing.
        var iOS = (/iP(hone|od|ad)/.test(Howler._navigator && Howler._navigator.platform));
        var appVersion = Howler._navigator && Howler._navigator.appVersion.match(/OS (\d+)_(\d+)_?(\d+)?/);
        var version = appVersion ? parseInt(appVersion[1], 10) : null;
        if (iOS && version && version < 9) {
            var safari = /safari/.test(Howler._navigator && Howler._navigator.userAgent.toLowerCase());
            if (Howler._navigator && Howler._navigator.standalone && !safari || Howler._navigator && !Howler._navigator.standalone && !safari) {
                Howler.usingWebAudio = false;
            }
        }

        // Create and expose the master GainNode when using Web Audio (useful for plugins or advanced usage).
        if (Howler.usingWebAudio) {
            Howler.masterGain = (typeof Howler.ctx.createGain === 'undefined') ? Howler.ctx.createGainNode() : Howler.ctx.createGain();
            Howler.masterGain.gain.setValueAtTime(Howler._muted ? 0 : 1, Howler.ctx.currentTime);
            Howler.masterGain.connect(Howler.ctx.destination);
        }

        // Re-run the setup on Howler.
        Howler._setup();
    };

    // Add support for AMD (Asynchronous Module Definition) libraries such as require.js.
    if (typeof define === 'function' && define.amd) {
        define([], function() {
            return {
                Howler: Howler,
                Howl: Howl
            };
        });
    }

    // Add support for CommonJS libraries such as browserify.
    if (typeof exports !== 'undefined') {
        exports.Howler = Howler;
        exports.Howl = Howl;
    }

    // Define globally in case AMD is not available or unused.
    if (typeof window !== 'undefined') {
        window.HowlerGlobal = HowlerGlobal;
        window.Howler = Howler;
        window.Howl = Howl;
        window.Sound = Sound;
    } else if (typeof global !== 'undefined') { // Add to global in Node.js (for testing, etc).
        global.HowlerGlobal = HowlerGlobal;
        global.Howler = Howler;
        global.Howl = Howl;
        global.Sound = Sound;
    }
})();


/*!
 *  Spatial Plugin - Adds support for stereo and 3D audio where Web Audio is supported.
 *  
 *  howler.js v2.0.14
 *  howlerjs.com
 *
 *  (c) 2013-2018, James Simpson of GoldFire Studios
 *  goldfirestudios.com
 *
 *  MIT License
 */

(function() {

    'use strict';

    // Setup default properties.
    HowlerGlobal.prototype._pos = [0, 0, 0];
    HowlerGlobal.prototype._orientation = [0, 0, -1, 0, 1, 0];

    /** Global Methods **/
    /***************************************************************************/

    /**
     * Helper method to update the stereo panning position of all current Howls.
     * Future Howls will not use this value unless explicitly set.
     * @param  {Number} pan A value of -1.0 is all the way left and 1.0 is all the way right.
     * @return {Howler/Number}     Self or current stereo panning value.
     */
    HowlerGlobal.prototype.stereo = function(pan) {
        var self = this;

        // Stop right here if not using Web Audio.
        if (!self.ctx || !self.ctx.listener) {
            return self;
        }

        // Loop through all Howls and update their stereo panning.
        for (var i=self._howls.length-1; i>=0; i--) {
            self._howls[i].stereo(pan);
        }

        return self;
    };

    /**
     * Get/set the position of the listener in 3D cartesian space. Sounds using
     * 3D position will be relative to the listener's position.
     * @param  {Number} x The x-position of the listener.
     * @param  {Number} y The y-position of the listener.
     * @param  {Number} z The z-position of the listener.
     * @return {Howler/Array}   Self or current listener position.
     */
    HowlerGlobal.prototype.pos = function(x, y, z) {
        var self = this;

        // Stop right here if not using Web Audio.
        if (!self.ctx || !self.ctx.listener) {
            return self;
        }

        // Set the defaults for optional 'y' & 'z'.
        y = (typeof y !== 'number') ? self._pos[1] : y;
        z = (typeof z !== 'number') ? self._pos[2] : z;

        if (typeof x === 'number') {
            self._pos = [x, y, z];

            if (typeof self.ctx.listener.positionX !== 'undefined') {
                self.ctx.listener.positionX.setTargetAtTime(self._pos[0], Howler.ctx.currentTime, 0.1);
                self.ctx.listener.positionY.setTargetAtTime(self._pos[1], Howler.ctx.currentTime, 0.1);
                self.ctx.listener.positionZ.setTargetAtTime(self._pos[2], Howler.ctx.currentTime, 0.1);
            } else {
                self.ctx.listener.setPosition(self._pos[0], self._pos[1], self._pos[2]);
            }
        } else {
            return self._pos;
        }

        return self;
    };

    /**
     * Get/set the direction the listener is pointing in the 3D cartesian space.
     * A front and up vector must be provided. The front is the direction the
     * face of the listener is pointing, and up is the direction the top of the
     * listener is pointing. Thus, these values are expected to be at right angles
     * from each other.
     * @param  {Number} x   The x-orientation of the listener.
     * @param  {Number} y   The y-orientation of the listener.
     * @param  {Number} z   The z-orientation of the listener.
     * @param  {Number} xUp The x-orientation of the top of the listener.
     * @param  {Number} yUp The y-orientation of the top of the listener.
     * @param  {Number} zUp The z-orientation of the top of the listener.
     * @return {Howler/Array}     Returns self or the current orientation vectors.
     */
    HowlerGlobal.prototype.orientation = function(x, y, z, xUp, yUp, zUp) {
        var self = this;

        // Stop right here if not using Web Audio.
        if (!self.ctx || !self.ctx.listener) {
            return self;
        }

        // Set the defaults for optional 'y' & 'z'.
        var or = self._orientation;
        y = (typeof y !== 'number') ? or[1] : y;
        z = (typeof z !== 'number') ? or[2] : z;
        xUp = (typeof xUp !== 'number') ? or[3] : xUp;
        yUp = (typeof yUp !== 'number') ? or[4] : yUp;
        zUp = (typeof zUp !== 'number') ? or[5] : zUp;

        if (typeof x === 'number') {
            self._orientation = [x, y, z, xUp, yUp, zUp];

            if (typeof self.ctx.listener.forwardX !== 'undefined') {
                self.ctx.listener.forwardX.setTargetAtTime(x, Howler.ctx.currentTime, 0.1);
                self.ctx.listener.forwardY.setTargetAtTime(y, Howler.ctx.currentTime, 0.1);
                self.ctx.listener.forwardZ.setTargetAtTime(z, Howler.ctx.currentTime, 0.1);
                self.ctx.listener.upX.setTargetAtTime(x, Howler.ctx.currentTime, 0.1);
                self.ctx.listener.upY.setTargetAtTime(y, Howler.ctx.currentTime, 0.1);
                self.ctx.listener.upZ.setTargetAtTime(z, Howler.ctx.currentTime, 0.1);
            } else {
                self.ctx.listener.setOrientation(x, y, z, xUp, yUp, zUp);
            }
        } else {
            return or;
        }

        return self;
    };

    /** Group Methods **/
    /***************************************************************************/

    /**
     * Add new properties to the core init.
     * @param  {Function} _super Core init method.
     * @return {Howl}
     */
    Howl.prototype.init = (function(_super) {
        return function(o) {
            var self = this;

            // Setup user-defined default properties.
            self._orientation = o.orientation || [1, 0, 0];
            self._stereo = o.stereo || null;
            self._pos = o.pos || null;
            self._pannerAttr = {
                coneInnerAngle: typeof o.coneInnerAngle !== 'undefined' ? o.coneInnerAngle : 360,
                coneOuterAngle: typeof o.coneOuterAngle !== 'undefined' ? o.coneOuterAngle : 360,
                coneOuterGain: typeof o.coneOuterGain !== 'undefined' ? o.coneOuterGain : 0,
                distanceModel: typeof o.distanceModel !== 'undefined' ? o.distanceModel : 'inverse',
                maxDistance: typeof o.maxDistance !== 'undefined' ? o.maxDistance : 10000,
                panningModel: typeof o.panningModel !== 'undefined' ? o.panningModel : 'HRTF',
                refDistance: typeof o.refDistance !== 'undefined' ? o.refDistance : 1,
                rolloffFactor: typeof o.rolloffFactor !== 'undefined' ? o.rolloffFactor : 1
            };

            // Setup event listeners.
            self._onstereo = o.onstereo ? [{fn: o.onstereo}] : [];
            self._onpos = o.onpos ? [{fn: o.onpos}] : [];
            self._onorientation = o.onorientation ? [{fn: o.onorientation}] : [];

            // Complete initilization with howler.js core's init function.
            return _super.call(this, o);
        };
    })(Howl.prototype.init);

    /**
     * Get/set the stereo panning of the audio source for this sound or all in the group.
     * @param  {Number} pan  A value of -1.0 is all the way left and 1.0 is all the way right.
     * @param  {Number} id (optional) The sound ID. If none is passed, all in group will be updated.
     * @return {Howl/Number}    Returns self or the current stereo panning value.
     */
    Howl.prototype.stereo = function(pan, id) {
        var self = this;

        // Stop right here if not using Web Audio.
        if (!self._webAudio) {
            return self;
        }

        // If the sound hasn't loaded, add it to the load queue to change stereo pan when capable.
        if (self._state !== 'loaded') {
            self._queue.push({
                event: 'stereo',
                action: function() {
                    self.stereo(pan, id);
                }
            });

            return self;
        }

        // Check for PannerStereoNode support and fallback to PannerNode if it doesn't exist.
        var pannerType = (typeof Howler.ctx.createStereoPanner === 'undefined') ? 'spatial' : 'stereo';

        // Setup the group's stereo panning if no ID is passed.
        if (typeof id === 'undefined') {
            // Return the group's stereo panning if no parameters are passed.
            if (typeof pan === 'number') {
                self._stereo = pan;
                self._pos = [pan, 0, 0];
            } else {
                return self._stereo;
            }
        }

        // Change the streo panning of one or all sounds in group.
        var ids = self._getSoundIds(id);
        for (var i=0; i<ids.length; i++) {
            // Get the sound.
            var sound = self._soundById(ids[i]);

            if (sound) {
                if (typeof pan === 'number') {
                    sound._stereo = pan;
                    sound._pos = [pan, 0, 0];

                    if (sound._node) {
                        // If we are falling back, make sure the panningModel is equalpower.
                        sound._pannerAttr.panningModel = 'equalpower';

                        // Check if there is a panner setup and create a new one if not.
                        if (!sound._panner || !sound._panner.pan) {
                            setupPanner(sound, pannerType);
                        }

                        if (pannerType === 'spatial') {
                            if (typeof sound._panner.positionX !== 'undefined') {
                                sound._panner.positionX.setValueAtTime(pan, Howler.ctx.currentTime);
                                sound._panner.positionY.setValueAtTime(0, Howler.ctx.currentTime);
                                sound._panner.positionZ.setValueAtTime(0, Howler.ctx.currentTime);
                            } else {
                                sound._panner.setPosition(pan, 0, 0);
                            }
                        } else {
                            sound._panner.pan.setValueAtTime(pan, Howler.ctx.currentTime);
                        }
                    }

                    self._emit('stereo', sound._id);
                } else {
                    return sound._stereo;
                }
            }
        }

        return self;
    };

    /**
     * Get/set the 3D spatial position of the audio source for this sound or group relative to the global listener.
     * @param  {Number} x  The x-position of the audio source.
     * @param  {Number} y  The y-position of the audio source.
     * @param  {Number} z  The z-position of the audio source.
     * @param  {Number} id (optional) The sound ID. If none is passed, all in group will be updated.
     * @return {Howl/Array}    Returns self or the current 3D spatial position: [x, y, z].
     */
    Howl.prototype.pos = function(x, y, z, id) {
        var self = this;

        // Stop right here if not using Web Audio.
        if (!self._webAudio) {
            return self;
        }

        // If the sound hasn't loaded, add it to the load queue to change position when capable.
        if (self._state !== 'loaded') {
            self._queue.push({
                event: 'pos',
                action: function() {
                    self.pos(x, y, z, id);
                }
            });

            return self;
        }

        // Set the defaults for optional 'y' & 'z'.
        y = (typeof y !== 'number') ? 0 : y;
        z = (typeof z !== 'number') ? -0.5 : z;

        // Setup the group's spatial position if no ID is passed.
        if (typeof id === 'undefined') {
            // Return the group's spatial position if no parameters are passed.
            if (typeof x === 'number') {
                self._pos = [x, y, z];
            } else {
                return self._pos;
            }
        }

        // Change the spatial position of one or all sounds in group.
        var ids = self._getSoundIds(id);
        for (var i=0; i<ids.length; i++) {
            // Get the sound.
            var sound = self._soundById(ids[i]);

            if (sound) {
                if (typeof x === 'number') {
                    sound._pos = [x, y, z];

                    if (sound._node) {
                        // Check if there is a panner setup and create a new one if not.
                        if (!sound._panner || sound._panner.pan) {
                            setupPanner(sound, 'spatial');
                        }

                        if (typeof sound._panner.positionX !== 'undefined') {
                            sound._panner.positionX.setValueAtTime(x, Howler.ctx.currentTime);
                            sound._panner.positionY.setValueAtTime(y, Howler.ctx.currentTime);
                            sound._panner.positionZ.setValueAtTime(z, Howler.ctx.currentTime);
                        } else {
                            sound._panner.setOrientation(x, y, z);
                        }
                    }

                    self._emit('pos', sound._id);
                } else {
                    return sound._pos;
                }
            }
        }

        return self;
    };

    /**
     * Get/set the direction the audio source is pointing in the 3D cartesian coordinate
     * space. Depending on how direction the sound is, based on the `cone` attributes,
     * a sound pointing away from the listener can be quiet or silent.
     * @param  {Number} x  The x-orientation of the source.
     * @param  {Number} y  The y-orientation of the source.
     * @param  {Number} z  The z-orientation of the source.
     * @param  {Number} id (optional) The sound ID. If none is passed, all in group will be updated.
     * @return {Howl/Array}    Returns self or the current 3D spatial orientation: [x, y, z].
     */
    Howl.prototype.orientation = function(x, y, z, id) {
        var self = this;

        // Stop right here if not using Web Audio.
        if (!self._webAudio) {
            return self;
        }

        // If the sound hasn't loaded, add it to the load queue to change orientation when capable.
        if (self._state !== 'loaded') {
            self._queue.push({
                event: 'orientation',
                action: function() {
                    self.orientation(x, y, z, id);
                }
            });

            return self;
        }

        // Set the defaults for optional 'y' & 'z'.
        y = (typeof y !== 'number') ? self._orientation[1] : y;
        z = (typeof z !== 'number') ? self._orientation[2] : z;

        // Setup the group's spatial orientation if no ID is passed.
        if (typeof id === 'undefined') {
            // Return the group's spatial orientation if no parameters are passed.
            if (typeof x === 'number') {
                self._orientation = [x, y, z];
            } else {
                return self._orientation;
            }
        }

        // Change the spatial orientation of one or all sounds in group.
        var ids = self._getSoundIds(id);
        for (var i=0; i<ids.length; i++) {
            // Get the sound.
            var sound = self._soundById(ids[i]);

            if (sound) {
                if (typeof x === 'number') {
                    sound._orientation = [x, y, z];

                    if (sound._node) {
                        // Check if there is a panner setup and create a new one if not.
                        if (!sound._panner) {
                            // Make sure we have a position to setup the node with.
                            if (!sound._pos) {
                                sound._pos = self._pos || [0, 0, -0.5];
                            }

                            setupPanner(sound, 'spatial');
                        }

                        if (typeof sound._panner.orientationX !== 'undefined') {
                            sound._panner.orientationX.setValueAtTime(x, Howler.ctx.currentTime);
                            sound._panner.orientationY.setValueAtTime(y, Howler.ctx.currentTime);
                            sound._panner.orientationZ.setValueAtTime(z, Howler.ctx.currentTime);
                        } else {
                            sound._panner.setOrientation(x, y, z);
                        }
                    }

                    self._emit('orientation', sound._id);
                } else {
                    return sound._orientation;
                }
            }
        }

        return self;
    };

    /**
     * Get/set the panner node's attributes for a sound or group of sounds.
     * This method can optionall take 0, 1 or 2 arguments.
     *   pannerAttr() -> Returns the group's values.
     *   pannerAttr(id) -> Returns the sound id's values.
     *   pannerAttr(o) -> Set's the values of all sounds in this Howl group.
     *   pannerAttr(o, id) -> Set's the values of passed sound id.
     *
     *   Attributes:
     *     coneInnerAngle - (360 by default) A parameter for directional audio sources, this is an angle, in degrees,
     *                      inside of which there will be no volume reduction.
     *     coneOuterAngle - (360 by default) A parameter for directional audio sources, this is an angle, in degrees,
     *                      outside of which the volume will be reduced to a constant value of `coneOuterGain`.
     *     coneOuterGain - (0 by default) A parameter for directional audio sources, this is the gain outside of the
     *                     `coneOuterAngle`. It is a linear value in the range `[0, 1]`.
     *     distanceModel - ('inverse' by default) Determines algorithm used to reduce volume as audio moves away from
     *                     listener. Can be `linear`, `inverse` or `exponential.
     *     maxDistance - (10000 by default) The maximum distance between source and listener, after which the volume
     *                   will not be reduced any further.
     *     refDistance - (1 by default) A reference distance for reducing volume as source moves further from the listener.
     *                   This is simply a variable of the distance model and has a different effect depending on which model
     *                   is used and the scale of your coordinates. Generally, volume will be equal to 1 at this distance.
     *     rolloffFactor - (1 by default) How quickly the volume reduces as source moves from listener. This is simply a
     *                     variable of the distance model and can be in the range of `[0, 1]` with `linear` and `[0, ∞]`
     *                     with `inverse` and `exponential`.
     *     panningModel - ('HRTF' by default) Determines which spatialization algorithm is used to position audio.
     *                     Can be `HRTF` or `equalpower`.
     *
     * @return {Howl/Object} Returns self or current panner attributes.
     */
    Howl.prototype.pannerAttr = function() {
        var self = this;
        var args = arguments;
        var o, id, sound;

        // Stop right here if not using Web Audio.
        if (!self._webAudio) {
            return self;
        }

        // Determine the values based on arguments.
        if (args.length === 0) {
            // Return the group's panner attribute values.
            return self._pannerAttr;
        } else if (args.length === 1) {
            if (typeof args[0] === 'object') {
                o = args[0];

                // Set the grou's panner attribute values.
                if (typeof id === 'undefined') {
                    if (!o.pannerAttr) {
                        o.pannerAttr = {
                            coneInnerAngle: o.coneInnerAngle,
                            coneOuterAngle: o.coneOuterAngle,
                            coneOuterGain: o.coneOuterGain,
                            distanceModel: o.distanceModel,
                            maxDistance: o.maxDistance,
                            refDistance: o.refDistance,
                            rolloffFactor: o.rolloffFactor,
                            panningModel: o.panningModel
                        };
                    }

                    self._pannerAttr = {
                        coneInnerAngle: typeof o.pannerAttr.coneInnerAngle !== 'undefined' ? o.pannerAttr.coneInnerAngle : self._coneInnerAngle,
                        coneOuterAngle: typeof o.pannerAttr.coneOuterAngle !== 'undefined' ? o.pannerAttr.coneOuterAngle : self._coneOuterAngle,
                        coneOuterGain: typeof o.pannerAttr.coneOuterGain !== 'undefined' ? o.pannerAttr.coneOuterGain : self._coneOuterGain,
                        distanceModel: typeof o.pannerAttr.distanceModel !== 'undefined' ? o.pannerAttr.distanceModel : self._distanceModel,
                        maxDistance: typeof o.pannerAttr.maxDistance !== 'undefined' ? o.pannerAttr.maxDistance : self._maxDistance,
                        refDistance: typeof o.pannerAttr.refDistance !== 'undefined' ? o.pannerAttr.refDistance : self._refDistance,
                        rolloffFactor: typeof o.pannerAttr.rolloffFactor !== 'undefined' ? o.pannerAttr.rolloffFactor : self._rolloffFactor,
                        panningModel: typeof o.pannerAttr.panningModel !== 'undefined' ? o.pannerAttr.panningModel : self._panningModel
                    };
                }
            } else {
                // Return this sound's panner attribute values.
                sound = self._soundById(parseInt(args[0], 10));
                return sound ? sound._pannerAttr : self._pannerAttr;
            }
        } else if (args.length === 2) {
            o = args[0];
            id = parseInt(args[1], 10);
        }

        // Update the values of the specified sounds.
        var ids = self._getSoundIds(id);
        for (var i=0; i<ids.length; i++) {
            sound = self._soundById(ids[i]);

            if (sound) {
                // Merge the new values into the sound.
                var pa = sound._pannerAttr;
                pa = {
                    coneInnerAngle: typeof o.coneInnerAngle !== 'undefined' ? o.coneInnerAngle : pa.coneInnerAngle,
                    coneOuterAngle: typeof o.coneOuterAngle !== 'undefined' ? o.coneOuterAngle : pa.coneOuterAngle,
                    coneOuterGain: typeof o.coneOuterGain !== 'undefined' ? o.coneOuterGain : pa.coneOuterGain,
                    distanceModel: typeof o.distanceModel !== 'undefined' ? o.distanceModel : pa.distanceModel,
                    maxDistance: typeof o.maxDistance !== 'undefined' ? o.maxDistance : pa.maxDistance,
                    refDistance: typeof o.refDistance !== 'undefined' ? o.refDistance : pa.refDistance,
                    rolloffFactor: typeof o.rolloffFactor !== 'undefined' ? o.rolloffFactor : pa.rolloffFactor,
                    panningModel: typeof o.panningModel !== 'undefined' ? o.panningModel : pa.panningModel
                };

                // Update the panner values or create a new panner if none exists.
                var panner = sound._panner;
                if (panner) {
                    panner.coneInnerAngle = pa.coneInnerAngle;
                    panner.coneOuterAngle = pa.coneOuterAngle;
                    panner.coneOuterGain = pa.coneOuterGain;
                    panner.distanceModel = pa.distanceModel;
                    panner.maxDistance = pa.maxDistance;
                    panner.refDistance = pa.refDistance;
                    panner.rolloffFactor = pa.rolloffFactor;
                    panner.panningModel = pa.panningModel;
                } else {
                    // Make sure we have a position to setup the node with.
                    if (!sound._pos) {
                        sound._pos = self._pos || [0, 0, -0.5];
                    }

                    // Create a new panner node.
                    setupPanner(sound, 'spatial');
                }
            }
        }

        return self;
    };

    /** Single Sound Methods **/
    /***************************************************************************/

    /**
     * Add new properties to the core Sound init.
     * @param  {Function} _super Core Sound init method.
     * @return {Sound}
     */
    Sound.prototype.init = (function(_super) {
        return function() {
            var self = this;
            var parent = self._parent;

            // Setup user-defined default properties.
            self._orientation = parent._orientation;
            self._stereo = parent._stereo;
            self._pos = parent._pos;
            self._pannerAttr = parent._pannerAttr;

            // Complete initilization with howler.js core Sound's init function.
            _super.call(this);

            // If a stereo or position was specified, set it up.
            if (self._stereo) {
                parent.stereo(self._stereo);
            } else if (self._pos) {
                parent.pos(self._pos[0], self._pos[1], self._pos[2], self._id);
            }
        };
    })(Sound.prototype.init);

    /**
     * Override the Sound.reset method to clean up properties from the spatial plugin.
     * @param  {Function} _super Sound reset method.
     * @return {Sound}
     */
    Sound.prototype.reset = (function(_super) {
        return function() {
            var self = this;
            var parent = self._parent;

            // Reset all spatial plugin properties on this sound.
            self._orientation = parent._orientation;
            self._stereo = parent._stereo;
            self._pos = parent._pos;
            self._pannerAttr = parent._pannerAttr;

            // If a stereo or position was specified, set it up.
            if (self._stereo) {
                parent.stereo(self._stereo);
            } else if (self._pos) {
                parent.pos(self._pos[0], self._pos[1], self._pos[2], self._id);
            } else if (self._panner) {
                // Disconnect the panner.
                self._panner.disconnect(0);
                self._panner = undefined;
                parent._refreshBuffer(self);
            }

            // Complete resetting of the sound.
            return _super.call(this);
        };
    })(Sound.prototype.reset);

    /** Helper Methods **/
    /***************************************************************************/

    /**
     * Create a new panner node and save it on the sound.
     * @param  {Sound} sound Specific sound to setup panning on.
     * @param {String} type Type of panner to create: 'stereo' or 'spatial'.
     */
    var setupPanner = function(sound, type) {
        type = type || 'spatial';

        // Create the new panner node.
        if (type === 'spatial') {
            sound._panner = Howler.ctx.createPanner();
            sound._panner.coneInnerAngle = sound._pannerAttr.coneInnerAngle;
            sound._panner.coneOuterAngle = sound._pannerAttr.coneOuterAngle;
            sound._panner.coneOuterGain = sound._pannerAttr.coneOuterGain;
            sound._panner.distanceModel = sound._pannerAttr.distanceModel;
            sound._panner.maxDistance = sound._pannerAttr.maxDistance;
            sound._panner.refDistance = sound._pannerAttr.refDistance;
            sound._panner.rolloffFactor = sound._pannerAttr.rolloffFactor;
            sound._panner.panningModel = sound._pannerAttr.panningModel;

            if (typeof sound._panner.positionX !== 'undefined') {
                sound._panner.positionX.setValueAtTime(sound._pos[0], Howler.ctx.currentTime);
                sound._panner.positionY.setValueAtTime(sound._pos[1], Howler.ctx.currentTime);
                sound._panner.positionZ.setValueAtTime(sound._pos[2], Howler.ctx.currentTime);
            } else {
                sound._panner.setPosition(sound._pos[0], sound._pos[1], sound._pos[2]);
            }

            if (typeof sound._panner.orientationX !== 'undefined') {
                sound._panner.orientationX.setValueAtTime(sound._orientation[0], Howler.ctx.currentTime);
                sound._panner.orientationY.setValueAtTime(sound._orientation[1], Howler.ctx.currentTime);
                sound._panner.orientationZ.setValueAtTime(sound._orientation[2], Howler.ctx.currentTime);
            } else {
                sound._panner.setOrientation(sound._orientation[0], sound._orientation[1], sound._orientation[2]);
            }
        } else {
            sound._panner = Howler.ctx.createStereoPanner();
            sound._panner.pan.setValueAtTime(sound._stereo, Howler.ctx.currentTime);
        }

        sound._panner.connect(sound._node);

        // Update the connections.
        if (!sound._paused) {
            sound._parent.pause(sound._id, true).play(sound._id, true);
        }
    };
})();